Abstract:

In a status detector for a power supply, a power supply, and an initial
characteristic extracting device for use with the power supply, a
measuring unit obtains measured values of at least current, voltage and
temperature of the electricity accumulating unit. A processing unit
executes status detection of the electricity accumulating unit by using
the measured values and the characteristic information of the electricity
accumulating unit which is stored in a memory unit. A discrepancy
detecting unit detects the presence of a discrepancy away from a
theoretical value when a result of the status detection is changed over a
predetermined threshold or reversed with respect to the measured values.
A modifying unit modifies the characteristic information depending on the
detected discrepancy.

Claims:

1. A status detector for a power supply, comprising:measuring means
capable of obtaining measured values of at least current, voltage and
temperature of electricity accumulating means;memory means for storing
characteristic information of said electricity accumulating
means;processing means for executing status detection of said electricity
accumulating means by using the measured values and the characteristic
information of said electricity accumulating means which is stored in
said memory means;discrepancy detecting means for detecting the presence
of a discrepancy away from a theoretical value when a result of the
status detection obtained by said processing means is changed over a
predetermined threshold or reversed with respect to the measured values
obtained by said measuring means; andmodifying means for modifying the
characteristic information stored in said memory means depending on the
discrepancy detected by said discrepancy detecting means.

[0003]The present invention relates to a status detector for a power
supply, a power supply, and an initial characteristic extracting device
for use with the power supply, each of which is suitable for detecting
the status of a battery (accumulator).

[0004]2. Description of the Related Art

[0005]In power supplies, decentralized power storages, and electric
vehicles using electricity accumulating units such as a lithium secondary
battery, a nickel-hydrogen battery, a lead-acid battery, and an electric
double-layer capacitor, a status detector for detecting the status of
each electricity accumulating unit is employed to ensure safe and
effective use of the electricity accumulating unit. The status of the
electricity accumulating unit includes, e.g., the state of charge (SOC)
or the remaining capacity indicating to what extent the unit is charged
or how much dischargeable charges remain, and the state of health (SOH)
or a deterioration level indicating how far the unit is deteriorated or
run down. In order to detect those states of the electricity accumulating
unit, it is also required to know characteristic information (such as
internal DC resistance) of the electricity accumulating unit beforehand.

[0006]SOC (State Of Charge) of a power supply used in portable equipment,
electric vehicles, etc. can be detected by integrating current discharged
from the fully charged state and calculating a ratio of the amount of
charges remaining in the electricity accumulating unit (i.e., the
remaining capacity) to the amount of maximally chargeable charges (i.e.,
the fully charged capacity). In many of the electricity accumulating
units, however, because the fully charged capacity is changed depending
on SOH (State Of Health), temperature, etc., it is difficult to
accurately detect SOC, taking into account those changes depending on
time and environment as well.

[0007]To overcome such a difficulty, there are known techniques as
follows. For example, JP-A-10-289734 (Patent Document 1) discloses that
an initial battery characteristic is modified in accordance with a
temperature modification coefficient computed based on a battery
temperature and a deterioration modification coefficient computed based
on a battery deterioration, and the remaining capacity of a battery is
computed based on not only the modified battery characteristic, but also
a discharge current and a terminal voltage during discharge.

[0008]Also, JP-A-11-218567 (Patent Document 2) discloses that a
deteriorated battery characteristic is computed by modifying an initial
battery characteristic based on respective relations to a temperature
modification coefficient, an internal resistance deterioration
modification coefficient, and a capacity deterioration modification
coefficient.

[0009]JP-A-2000-166105 (Patent Document 3) discloses that the state of
charge is detected based on a charge or discharge current, the state of
accumulated electricity is detected based on a voltage, and the state of
charge is controlled in accordance with the detected results.

[0010]JP-A-2000-166109 (Patent Document 4) discloses that an electromotive
voltage is determined from a charge or discharge current and a voltage,
and a charge characteristic is computed based on the relationship between
the electromotive voltage and the charge characteristic.

[0011]Further, JP-A-2001-85071 (Patent Document 5) discloses that a
temperature of each of combined battery modules is estimated based on a
voltage between respective two terminals and a current flowing through
each terminal.

SUMMARY OF THE INVENTION

[0012]However, the following problems are still left with the related art.
According to the method disclosed in JP-A-10-289734, influences of
temperature and deterioration are taken into consideration as the
temperature modification coefficient and the deterioration modification
coefficient, and parameters necessary for calculating the remaining
capacity are modified using those modification coefficients which have
been obtained through complicated computing processes. Accordingly, there
remain questions as to whether values of the modification coefficients
are correct in themselves, and whether all battery characteristics are
modified.

[0013]In addition, because some type of electricity accumulating unit has
characteristics such as charge efficiency and memory effect, those
characteristics have to be also taken into consideration in the
modification process to estimate the remaining capacity with high
accuracy. Moreover, because initial characteristics of electricity
accumulating units have individual differences, those individual
differences have to be further taken into consideration in the
modification process to estimate the remaining capacity with high
accuracy.

[0014]Stated another way, in order to perform the status detection, e.g.,
the estimation of the remaining capacity, with high accuracy, it is
required to faithfully make modeling of characteristics of the
electricity accumulating unit and to take a plurality of parameters into
account. Further, modification has to be performed in consideration of
changes of those parameters depending on time and environment.

[0015]Thus, a great deal of time and labor are consumed to obtain initial
characteristics and plural parameters of the electricity accumulating
unit and to acquire data of the modification coefficients. In spite of
processing being executed in a how complicated manner, however, the
processing result falls within the scope of theory regarding battery
characteristics or estimation based on a model, thus accompanying with a
question as to whether the estimated result is correct with respect to a
true value.

[0016]An object of the present invention is to provide a status detector
for a power supply, a power supply, and an initial characteristic
extracting device for use with the power supply, each of which can detect
the status of an electricity accumulating unit with high accuracy.

[0017]The present invention provides a status detector for a power supply,
which can detect the status of an electricity accumulating unit with high
accuracy.

[0018]According to one major aspect of the present invention, the status
detector for the power supply comprises a measuring unit capable of
obtaining measured values of at least current, voltage and temperature of
electricity accumulating unit; a memory unit for storing characteristic
information of the electricity accumulating unit; a processing unit for
executing status detection of the electricity accumulating unit by using
the measured values and the characteristic information of the electricity
accumulating unit which is stored in the memory unit; a discrepancy
detecting unit for detecting the presence of a discrepancy away from a
theoretical value when a result of the status detection obtained by the
processing unit is changed over a predetermined threshold or reversed
with respect to the measured values obtained by the measuring unit; and a
modifying unit for modifying the characteristic information stored in the
memory unit depending on the discrepancy detected by the discrepancy
detecting unit.

[0019]Also, the present invention provides a power supply, which can
detect the status of an electricity accumulating unit with high accuracy.

[0020]According to another major aspect of the present invention, the
power supply comprises an electricity accumulating unit capable of being
charged and discharged; a measuring unit for obtaining information of the
electricity accumulating unit during charge and discharge; and a status
detecting unit for detecting status of the electricity accumulating unit,
the status detecting unit comprising: a measuring unit capable of
obtaining measured values of at least current, voltage and temperature of
the electricity accumulating unit; a memory unit for storing
characteristic information of the electricity accumulating unit; a
processing unit for executing status detection of the electricity
accumulating unit by using the measured values and the characteristic
information of the electricity accumulating unit which is stored in the
memory unit; a discrepancy detecting unit for detecting the presence of a
discrepancy away from a theoretical value when a result of the status
detection obtained by the processing unit is changed over a predetermined
threshold or reversed with respect to the measured values obtained by the
measuring unit; and a modifying unit for modifying the characteristic
information stored in the memory unit depending on the discrepancy
detected by the discrepancy detecting unit.

[0021]Further, the present invention provides an initial characteristic
extracting device for use with a power supply, which can detect the
status of an electricity accumulating unit with high accuracy.

[0022]According to still another major aspect of the present invention,
the initial characteristic extracting device for use with the power
supply comprises an electricity accumulating unit capable of being
charged and discharged; a measuring unit for obtaining information of the
electricity accumulating unit during charge and discharge; and a status
detecting unit for detecting status of the electricity accumulating unit,
the status detecting unit comprising: a measuring unit capable of
obtaining measured values of at least current, voltage and temperature of
the electricity accumulating unit; a memory unit for storing
characteristic information of the electricity accumulating unit; a
processing unit for executing status detection of the electricity
accumulating unit by using the measured values and the characteristic
information of the electricity accumulating unit which is stored in the
memory unit; a discrepancy detecting unit for detecting the presence of a
discrepancy away from a theoretical value when a result of the status
detection obtained by the processing unit is changed over a predetermined
threshold or reversed with respect to the measured values obtained by the
measuring unit; and a modifying unit for modifying the characteristic
information stored in the memory unit depending on the discrepancy
detected by the discrepancy detecting unit, the initial characteristic
extracting device further comprising a charging/discharging device for
charging and discharging the electricity accumulating unit in accordance
with a predetermined pulse pattern, the charging/discharging device
performing charge and discharge of the electricity accumulating unit, the
measuring unit measuring the information of the electricity accumulating
unit during the charge and the discharge, the processing unit detecting
the status of the electricity accumulating unit by using the measured
values and the characteristic information of the electricity accumulating
unit which is stored in the memory unit, the discrepancy detecting unit
detecting the presence of a discrepancy of the detected status away from
the theoretical value, and the modifying unit modifying the
characteristic information such that the characteristic information is
converged within a certain range and the converged characteristic
information is extracted as an initial characteristic of the electricity
accumulating unit.

[0023]According to the present invention, it is possible to detect the
status of the electricity accumulating unit with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a block diagram showing the configuration of a power
supply according to a first embodiment of the present invention;

[0025]FIG. 2 is a flowchart showing processing procedures executed by a
status detecting unit used in the power supply according to the first
embodiment of the present invention;

[0026]FIG. 3 is a circuit diagram showing an equivalent circuit of an
electricity accumulating unit used in the power supply according to the
first embodiment of the present invention;

[0027]FIG. 4 is a graph for explaining the characteristic information
between OCV (Open Circuit Voltage) and SOC (State Of Charge) in the power
supply according to the first embodiment of the present invention;

[0028]FIGS. 5A and 5B are charts for explaining changes of current and SOC
during charge in the power supply according to the first embodiment of
the present invention;

[0029]FIG. 6 is a graph showing SOC and allowable currents of the
electricity accumulating unit in the power supply according to the first
embodiment of the present invention;

[0030]FIG. 7 is a flowchart showing the operation of a discrepancy
detecting unit in a power supply according to a second embodiment of the
present invention;

[0031]FIG. 8 is a block diagram showing the configuration of a processing
unit in a status detecting unit used in a power supply according to a
third embodiment of the present invention;

[0032]FIG. 9 is a graph for explaining temperature-dependent changes of
internal DC resistance of an electricity accumulating unit used in the
power supply according to the third embodiment of the present invention;

[0033]FIG. 10 is a block diagram showing the configuration of a power
supply according to a fourth embodiment of the present invention;

[0034]FIGS. 11A, 11B and 11C are graphs for explaining changes of SOC when
an electricity accumulating unit in the power supply according to the
fourth embodiment of the present invention is deteriorated;

[0035]FIG. 12 is a flowchart showing processing procedures executed by a
deterioration determining unit used in the power supply according to the
fourth embodiment of the present invention;

[0036]FIG. 13 is a block diagram showing the configuration of an initial
characteristic extracting device for use with a power supply according to
a fifth embodiment of the present invention;

[0037]FIG. 14 is a flowchart showing processing procedures executed by a
charging/discharging device in the initial characteristic extracting
device for use with the power supply according to the fifth embodiment of
the present invention;

[0038]FIG. 15 is a chart for explaining the charging/-discharging device
in the initial characteristic extracting device for use with the power
supply according to the fifth embodiment of the present invention;

[0039]FIG. 16 is a block diagram showing the configuration of a second
initial characteristic extracting device for use with a power supply
according to a sixth embodiment of the present invention;

[0040]FIGS. 17A and 17B are charts for explaining an initial
characteristic extracting method in the power supply according to the
sixth embodiment of the present invention;

[0041]FIG. 18 is a block diagram showing the configuration of a third
initial characteristic extracting device for use with a power supply
according to a seventh embodiment of the present invention;

[0042]FIG. 19 is a chart for explaining an initial characteristic
extracting method in the power supply according to the seventh embodiment
of the present invention; and

[0043]FIG. 20 is a block diagram showing the configuration of a fourth
initial characteristic extracting device for use with a power supply
according to an eighth embodiment of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044]The configuration and operation of a power supply according to a
first embodiment of the present invention will be described below with
reference to FIGS. 1-6.

[0045]The configuration of the power supply according to this embodiment
will be first described with reference to FIG. 1.

[0046]FIG. 1 is a block diagram showing the configuration of the power
supply according to the first embodiment of the present invention.

[0047]The power supply of this embodiment comprises a status detecting
unit 100, an electricity accumulating unit 200, a measuring unit 300, and
an output unit 400. The electricity accumulating unit 200 serves to
accumulate electricity and discharge the accumulated electricity, and it
is, e.g., a lithium secondary battery. This embodiment can also be
applied to the case of using, as the electricity accumulating unit 200,
other similar device with the function of storing electricity, such as a
nickel-hydrogen battery, a lead-acid battery, and an electric
double-layer capacitor. The electricity accumulating unit 200 may be a
single cell or may have a modular structure including a plurality of
single cells combined with each other.

[0048]The measuring unit 300 is constituted by sensors and electrical
circuits for obtaining information (such as a voltage V, a current I, and
a temperature T) of the electricity accumulating unit 200.

[0050]The processing unit 110 computes SOC (State Of Charge) of the
electricity accumulating unit 200 based on measured values (V, I, T)
obtained from the measuring unit 300 and characteristic information
(including a polarization voltage Vp and an internal DC resistance R) of
the electricity accumulating unit 200, which is read out of the memory
unit 130.

[0051]The processing unit 110 is constituted by, e.g., a microprocessor or
a computer. An SOC computing method executed by the processing unit 110
will be described later with reference to FIGS. 3 and 4.

[0052]The discrepancy detecting unit 120 monitors whether there is such a
discrepancy that the result obtained by the processing unit 110 is away
from a theoretical value, based on the measured value (I) obtained from
the measuring unit 300 and the SOC computed by the processing unit 110.
If the result obtained by the processing unit 110 is away from the
theoretical value, this is detected as being a discrepancy. A practical
discrepancy detecting method executed by the discrepancy detecting unit
120 will be described later with reference to FIGS. 5 and 6.

[0053]The modifying unit 140 modifies the characteristic information
(e.g., the polarization voltage Vp and the internal DC resistance R)
stored in the memory unit 130. The modifying unit 140 may be started only
when the discrepancy detecting unit 120 detects a discrepancy away from
the theoretical value, or it may be started regardless of whether there
is a discrepancy away from the theoretical value.

[0054]When the modifying unit 140 is started regardless of whether there
is a discrepancy away from the theoretical value, it modifies the
characteristic information using a predetermined modification amount if
the discrepancy detecting unit 120 detects a discrepancy away from the
theoretical value. If there is no discrepancy away from the theoretical
value, the characteristic information is modified with the modification
amount set to 0. Also, the modifying unit 140 modifies the characteristic
information depending on the nature of a discrepancy away from the
theoretical value, which has been detected by the discrepancy detecting
unit 120. The operation of the modifying unit 140 will be described
later.

[0055]The memory unit 130 stores the characteristic information that can
be obtained from the electricity accumulating unit 200 in advance, such
as the internal DC resistance, the polarization voltage, the charge
efficiency, the allowable current, and the fully charged capacity. These
items of the characteristic information may have characteristic values
for each of charge and discharge, or may have values depending on the
status of the electricity accumulating unit 200, such as SOC or
temperature. As an alternative, each item of the characteristic
information may be set to one value common to all states of the
electricity accumulating unit 200.

[0056]The memory unit 130 is formed of any suitable memory, e.g., a flash
memory, EEPROM, or a magnetic disk. The memory unit 130 may be provided
externally of the processing unit 110, or may be an internal memory
incorporated inside the processing unit 110. In addition to the
characteristic information of the electricity accumulating unit 200, the
memory unit 130 may store processing procedures for detecting the status
of the electricity accumulating unit 200.

[0057]The memory unit 130 may be removal. When the memory unit 130 is made
removal, the characteristic information and the processing procedures can
be easily changed by replacing the memory unit 130. Further, by preparing
a plurality of replaceable memory units 130 and storing the
characteristic information and the processing procedures in those memory
units 130 in a distributed way, it is possible to more finely update the
characteristic information and the processing procedures.

[0059]The operation of the status detecting unit 100 in the power supply
of this embodiment will be described below with reference to FIGS. 2-6.

[0060]Overall processing executed by the status detecting unit 100 in the
power supply of this embodiment will be described with reference to FIG.
2.

[0061]FIG. 2 is a flowchart showing processing procedures executed by the
status detecting unit used in the power supply according to the first
embodiment of the present invention.

[0062]In step S10 of FIG. 2, the processing unit 110 executes status
detection by computing SOC of the electricity accumulating unit 200 based
on the measured values (V, I, T) of the electricity accumulating unit 200
and the characteristic information (including the polarization voltage Vp
and the internal DC resistance R) of the electricity accumulating unit
200, which is read out of the memory unit 130.

[0063]A description is here made of processing procedures of the
processing unit 110 in the status detecting unit 100 of this embodiment
with reference to FIGS. 3 and 4.

[0064]FIG. 3 is a circuit diagram showing an equivalent circuit of the
electricity accumulating unit used in the power supply according to the
first embodiment of the present invention. FIG. 4 is a graph for
explaining the characteristic information between OCV (Open Circuit
Voltage) and SOC (State Of Charge) in the power supply according to the
first embodiment of the present invention.

[0065]FIG. 3 shows an equivalent circuit of the electricity accumulating
unit 200. The electricity accumulating unit 200 is represented by an
in-series connection containing a pair of an impedance Z and a
capacitance component C connected in parallel, an internal DC resistance
R, and an electromotive force OCV.

[0066]When a current I is applied to the electricity accumulating unit
200, an inter-terminal voltage (CCV; Closed Circuit Voltage) of the
electricity accumulating unit 200 is expressed by the following formula
(1);

CCV=OCV+IR+Vp (1)

In this formula, Vp represents the polarization voltage and corresponds to
a voltage across the pair of the impedance Z and the capacitance
component C connected in parallel.

[0067]The electromotive force OCV is used for computing SOC, but it cannot
be directly measured in a condition that the electricity accumulating
unit 200 is being charged or discharged. Therefore, the electromotive
force OCV is computed by subtracting an IR drop and the polarization
voltage Vp from the electromotive force CCV as expressed by the following
formula (2).

OCV=CCV-IR--Vp (2)

Here, the internal DC resistance R and the polarization voltage Vp can be
obtained from the characteristic information stored in the memory unit
130. The internal DC resistance R and the polarization voltage Vp have
values depending on the SOC, temperature, etc. of the electricity
accumulating unit 200. The current value I is obtained from a value
measured by the measuring unit 300.

[0068]FIG. 4 shows the relationship between the electromotive force OCV
and SOC. After the electromotive force OCV is computed using the current
value I, the internal DC resistance R and the polarization voltage Vp
based on the formula (2), the SOC of the electricity accumulating unit
200 can be estimated from the characteristic information between the
electromotive force OCV and SOC, which has been obtained in advance.

[0070]Returning to FIG. 2, in step S20, the discrepancy detecting unit 120
monitors whether there is a discrepancy away from the theoretical value,
based on the SOC received from the processing unit 110 and the measured
value (I) received from the measuring unit 300. If there is no
discrepancy, the control flow proceeds to step S50, and if there is a
discrepancy, the control flow proceeds to step S30.

[0071]A description is here made of processing procedures of the
discrepancy detecting unit 120 in the status detecting unit 100 of this
embodiment with reference to FIGS. 5 and 6.

[0072]FIGS. 5A and 5B are charts for explaining changes of current and SOC
during charge in the power supply according to the first embodiment of
the present invention.

[0073]FIG. 5A shows change of the current, and FIG. 5B shows change of the
SOC obtained by the processing unit 110. As shown in FIG. 5A, when charge
to the electricity accumulating unit 200 is started at a time t1, the
current I changes from 0 to a positive value. Correspondingly, as shown
in FIG. 5B, the result (SOC) of the status detection computed by the
processing unit 110 starts to increase from the time t1.

[0074]At that time, the discrepancy detecting unit 120 monitors whether
the increase of SOC does not exceed a predetermined threshold Th. If the
SOC has increased over the predetermined threshold Th as shown in FIG.
5B, the discrepancy detecting unit 120 determines that the change of SOC
is excessive and is discrepant away from the theoretical value.

[0075]The foregoing is related to the state of starting the charge. When
the current value I is reduced from 0 in the discharge state, the
discrepancy detecting unit 120 monitors a decrease of SOC, i.e., a
decrease of the result computed by the processing unit 110. If the SOC
has decreased over the predetermined threshold Th, the discrepancy
detecting unit 120 determines that the change of SOC is discrepant away
from the theoretical value, thus indicating detection of a discrepancy.

[0076]The threshold Th used for determining whether the change of SOC is
excessive is obtained using an allowable maximum charge or discharge
current value Imax and a fully charged capacity Qmas, which are derived
from the performance of the electricity accumulating unit 200, based on
the following formula (3)

Th=ΔSOCmax=100×Imax/Qmax (3)

Looking from the specific performance of the electricity accumulating unit
200, the SOC will never change over ΔSOCmax no matter what
condition is. Accordingly, if the computed SOC has increased or decreased
over ΔSOCmax, this can be determined as indicating a discrepancy
away from the theoretical value.

[0077]The case of changing the threshold Th depending on the performance
and status of the electricity accumulating unit 200 will be described
with reference to FIG. 6.

[0078]FIG. 6 is a graph showing SOC and allowable currents of the
electricity accumulating unit in the power supply according to the first
embodiment of the present invention.

[0079]As shown in FIG. 6, as the SOC increases, an allowable charge
current is increased, while an allowable discharge current is decreased.
Assuming an upper limit voltage and a lower limit voltage of the
electricity accumulating unit 200 to be Vmax and Vmin, an allowable
charge current Icmax and an allowable discharge current Idmax are
expressed by the following formulae (4) and (5), respectively;

Icmax=(Vmax-OCV)/Rz (4)

Idmax=(OCV-Vmin)/Rz (5)

wHere Rz represents an equivalent impedance of R, Z and C shown in FIG. 3.

[0080]An SOC maximum increase amount ΔSOCcmax during charge and an
SOC maximum decrease amount ΔSOCdmax during discharge depending on
the performance, temperature and SOC of the electricity accumulating unit
200 are obtained using the fully charged capacity Qmax of the electricity
accumulating unit 200 based on the following formulae (6) and (7),
respectively:

ΔSOCcmax=100×Icmax/Qmax (6)

ΔSOCdmax=100×Idmax/Qmax (7)

[0081]The SOC of the electricity accumulating unit 200 will never increase
over ΔSOCcmax during charge and it will never decrease over
ΔSOCdmax during discharge. Accordingly, the discrepancy detecting
unit 120 can use each of ΔSOCcmax and ΔSOCdmax as the
threshold Th that is variable depending on the performance, temperature
and SOC of the electricity accumulating unit 200. In other words, a
discrepancy can be detected by using the SOC maximum increase amount
ΔSOCcmax during charge and the SOC maximum decrease amount
ΔSOCdmax during discharge not only when the current is stepwisely
changed as in the state of starting charge, as shown in FIG. 5, but also
when the current is moderately changed.

[0082]The above-described manner of deciding the threshold Th represents
the case where the performance of the electricity accumulating unit 200
is taken into consideration. By additionally considering the maximum
allowable charge and discharge currents depending on a system in which
the electricity accumulating unit 200 is used as the power supply, the
threshold Th can be decided with higher reliability. To describe a manner
of deciding the threshold Th during discharge, for example, even with the
maximum allowable discharge current of the electricity accumulating unit
itself being 200 A, when the electricity accumulating unit is used in an
actual system in the form of a vehicle, a maximum current value used in
the system is 100 A in some case. In that case, the threshold Th can be
decided by using 100 A as the maximum allowable discharge current. To
describe a manner of deciding the threshold Th during charge, even with
the maximum allowable charge current of the electricity accumulating unit
itself being 200 A, when the electricity accumulating unit is used in an
actual system in the form of a vehicle, a maximum generation current of a
generator motor (M/G) used as an alternator or a generator is 100 A in
some case. In that case, the threshold Th can be decided by using 100 A
as the maximum allowable charge current.

[0083]Returning to FIG. 2, if a discrepancy is detected in step S20, the
modifying unit 140 modifies the characteristic information and stores the
modified characteristic information in the memory unit 130 in step S30.

[0084]To cope with the discrepancy away from the theoretical value, the
modifying unit 140 increases the value of the internal DC resistance R
and stores a modified internal DC resistance R' as new characteristic
information in the memory unit 130 to be used from the subsequent
processing as the new characteristic information.

[0085]The internal DC resistance R may be modified by increasing the
resistance value by 1%, or by a minimum unit for the value representing
the characteristic information. As another method, a modification amount
may be set to be larger as the discrepancy away from the theoretical
value is increased, and to be smaller as the discrepancy away from the
theoretical value is decreased. The minimum unit for the value
representing the characteristic information means a minimum unit
corresponding to a digit of the internal DC resistance, which can be
distinctively stored in the memory unit 130. Assuming a minimum value of
the internal DC resistance to be, e.g., 0.1 mΩ, the internal DC
resistance is increased in units of 0.1 mΩ.

[0086]When it is desired to dynamically change the modification, the
following method can be used, by way of example. If the SOC is changed
over the threshold Th, the state of charge SOCth is obtained using the
state of charge SOCold in the preceding cycle based on the following
formula (8):

SOCth=SOCold+Th (8)

[0087]An electromotive force OCVth corresponding to the state of charge
SOCth can be obtained from the relationship between the electromotive
force OCV and SOC shown in FIG. 4. By using the obtained OCVth, the
formula (2) can be rewritten to the following formula (9):

OCVth=CCV-IRth-Vp (9)

By rearranging the formula (9), Rth providing change of SOC, which will
not exceed the threshold Th, can be expressed by the following formula
(10):

Rth=(CCV-OCVth-Vp)/I (10)

[0088]The modifying unit 140 modifies the internal DC resistance so that
Rth expressed by the formula (10) is obtained. Thus, the modification
amount of the characteristic information can be changed in a dynamic
manner.

[0089]The operation of the discrepancy detecting unit 120 will be
described below in connection with the case where the current value I
measured by the measuring unit 300 indicates charge and the result of the
status detection executed by the processing unit 110 shows a decrease of
SOC, or the case where the current value indicates discharge and the
result of the status detection shows an increase of SOC.

[0090]When the current value I of the electricity accumulating unit 200
measured by the measuring unit 300 indicates charge and the result of the
status detection executed by the processing unit 110 shows a decrease of
SOC, i.e., "reversal", the discrepancy detecting unit 120 detects such a
condition to be a discrepancy away from the theoretical value. Also, when
the current value I measured by the measuring unit 300 indicates
discharge and the result of the status detection shows an increase of
SOC, i.e., "reversal", the discrepancy detecting unit 120 similarly
detects such a condition to be a discrepancy away from the theoretical
value.

[0091]The discrepancy detecting unit 120 may determine the detection of a
discrepancy in the case where the SOC shows the reversal even just a
little with respect to the measured current value, or may determine the
detection of a discrepancy with a margin allowing the reversal of SOC up
to a predetermined value set within the range not exceeding the threshold
Th.

[0092]When the reversal of SOC is detected, the modifying unit 140 makes
modification to decrease the value of the internal DC resistance R. An
internal DC resistance R' modified by a predetermined amount is stored as
new characteristic information in the memory unit 130, and the stored new
characteristic information is used from the subsequent processing.

[0093]Table 1, given below, lists the operation of the discrepancy
detecting unit 120 to detect a discrepancy away from the theoretical
value, the cause of the discrepancy, and a modification action executed
by the modifying unit 140 to overcome the discrepancy. As seen from Table
1, the discrepancy detecting unit 120 detects, as a discrepancy away from
the theoretical value, the excessive change of SOC caused by too small R
and the reversal of SOC caused by too large R, and the modifying unit 140
modifies R depending on the nature of the discrepancy. Accordingly, the
status detection of the electricity accumulating unit 200 can be
performed by using R that causes neither the excessive change of SOC nor
the reversal of SOC.

[0094]Returning to FIG. 2, in step S40, the processing unit 110 detects
the status of the electricity accumulating unit 200 again by using the
new characteristic information so that the result of the status detection
is obtained with higher accuracy.

[0095]Then, in step S50 of FIG. 2, the obtained result of the status
detection is transmitted to the output unit 400 and is outputted to the
exterior from the output unit 400.

[0096]In the above description, the discrepancy detecting unit 120 and the
modifying unit 140, shown in FIG. 1, may be constituted by separate
microprocessors or computers. As an alternative, the discrepancy
detecting unit 120 and the modifying unit 140 may be realized with one
microprocessor or computer that executes the processing of both the units
120 and 140 together. The processing unit 110, the discrepancy detecting
unit 120, and the modifying unit 140 are interconnected via communication
units capable of transferring information and commands among them.

[0097]While the discrepancy detecting unit 120 and the modifying unit 140
are shown in FIG. 1 as being installed externally of the processing unit
110, those units may be constituted in the forms of program modules or
subroutines executing the above-described processing procedures, and may
be realized with one processing sequence containing the processing
procedures of both the discrepancy detecting unit 120 and the modifying
unit 140 together. In that case, the discrepancy detecting unit 120 and
the modifying unit 140 are stored as software in the memory unit 130 and
executed by the processing unit 110.

[0098]The output unit 400 comprises LAN, CAN, radio LAN or short-range
radio communication utilizing the so-called CSMA/CD system, or a device
for transferring an ON-OFF signal, such as a photocoupler or a relay, and
an associated circuit. The output unit 400 may use wired communication or
radio communication. A display unit, such as a display monitor, may be
used as the output unit 400 to display only the result of the current
status detection or to display a time-serial graph in which the results
of the current and past status detections are indicated together.

[0099]Further, by employing a microcomputer in which an A/D converter, a
flash memory, a microprocessor and a communication circuit are
constituted on the same device, the measuring unit 300, the memory unit
130, the processing unit 110, the discrepancy detecting unit 120, the
modifying unit 140, and the output unit 400 used in this embodiment can
be constituted on the same device. Additionally, those units can be
shared by another control unit.

[0100]According to this embodiment, as described above, when the
discrepancy detecting unit 120 detects the excessive change of SOC, the
modification to increase the internal DC resistance R is performed, and
when the discrepancy detecting unit 120 detects the reversal of SOC, the
modification to decrease the internal DC resistance R is performed. As a
result, the status of the electricity accumulating unit 200 can be
detected with high accuracy in spite of parameters being changed
depending on time and environment.

[0101]The configuration and operation of a power supply according to a
second embodiment of the present invention will be described below with
reference to FIGS. 1 and 7.

[0102]FIG. 7 is a flowchart showing the operation of a discrepancy
detecting unit in the power supply according to the second embodiment of
the present invention;

[0103]The overall configuration of the power supply according to this
embodiment is the same as that shown in FIG. 1. In this embodiment,
processing procedures executed by the discrepancy detecting unit 120
differs from those shown in FIG. 2.

[0104]After charge or discharge of the electricity accumulating unit 200
has finished, i.e., when the current value among the measured values has
come into a state indicating 0 A, it is normal that the SOC will not
change in environment where self-discharge is negligible. In view of that
fact, the discrepancy detecting unit 120 monitors the SOC obtained by the
processing unit 110 after the charge or discharge has finished. If a
change is found in the estimated SOC, this is detected as indicating a
discrepancy away from the theoretical value.

[0105]A practical discrepancy detecting method executed by the discrepancy
detecting unit 120 will be described below with reference to FIG. 7.

[0106]In step S100, the discrepancy detecting unit 120 set 0 in a counter
prepared for counting the number of estimation results of SOC.

[0107]Then, in step S110, the discrepancy detecting unit 120 monitors the
current value among the measured values, and when the current value has
become 0 A, it determines that the charge or discharge of the electricity
accumulating unit 200 has finished.

[0108]Then, in step S120, the result of detecting the status of the
electricity accumulating unit 200 after determination that the charge or
discharge has finished, is stored in, e.g., a rewritable memory within
the processing unit 110. In step S130, a value of the counter is
incremented by one. At this time, the value set in the counter is 1.

[0109]Then, in step S140, the discrepancy detecting unit 120 monitors
whether the counter value exceeds a predetermined threshold that has been
prepared in advance. If the counter value does not exceed the
predetermined threshold, the control flow returns to step S110. In step
S110, the present status of the electricity accumulating unit 200 is
monitored, and if neither charge nor discharge is being performed, the
result of detecting the status of the electricity accumulating unit 200
is stored in addition to the previously stored result. The counter value
is further incremented by one to become 2 at this time. The
above-described procedures are repeated until the counter value exceeds
the predetermined threshold, while successively storing the estimation
results of SOC after the end of the charge and discharge.

[0110]If the counter value exceeds the predetermined threshold, the
discrepancy detecting unit 120 analyzes, in step S150, the plural results
of the status detection which have been stored in the memory, thereby
confirming a change of SOC in the condition where the electricity
accumulating unit 200 is under neither charge nor discharge. Because the
results stored in the memory correspond to the condition where the
electricity accumulating unit 200 is under neither charge nor discharge,
it is normal that the change of SOC is not found. Accordingly, if the
change of SOC is found, the discrepancy detecting unit 120 determines
that there occurs a discrepancy away from the theoretical value.

[0112]The threshold is set to a value of 2 or more. When the threshold is
set to 2, care should be paid because of a possibility that the change of
SOC caused by a sensing error or the like may be detected as indicating a
discrepancy away from the theoretical value.

[0113]The modifying unit 140 may be started only when the discrepancy
detecting unit 120 detects a discrepancy away from the theoretical value,
or it may be always started even when no discrepancy is detected. In the
latter case, the modifying unit 140 modifies the polarization voltage Vp
with a modification amount set to 0 when no discrepancy is detected, and
it modifies the polarization voltage Vp by a predetermined modification
amount when a discrepancy is detected.

[0114]If the measured value other than the current of 0 A is received
before the counter value exceeds the predetermined threshold, i.e., if
the charge or discharge of the electricity accumulating unit 200 is
started before the same, the stored results of the status detection is
erased and the counter value is reset to 0. When the current of 0 A is
detected next, the above-described processing is executed in a similar
way.

[0115]A description is now made of a discrepancy detecting method executed
by the discrepancy detecting unit 120 when the counter value exceeds the
predetermined threshold. When the counter value exceeds the predetermined
threshold, the discrepancy detecting unit 120 analyzes the two or more
estimation results of SOC stored in the memory, and confirms a
time-serial change of SOC. The time-serial change of SOC can be formed by
using, e.g., the least square method. More specifically, by approximating
two or more values of SOC with a linear line based on the least square
method, the time-serial change of SOC can be expressed by a gradient k of
the linear line. As an alternative, the time-serial change of SOC may be
confirmed by totalizing time-serial change amounts of the stored
estimation results of SOC, dividing the total change amount by the number
of the stored estimation results of SOC to obtain an average change
amount of SOC, and defining the average change amount as a change k of
SOC.

[0116]Table 2, given below, lists the change k of SOC, which represents a
discrepancy away from the theoretical value after the end of charge and
discharge, and the modification of the polarization voltage Vp, which is
executed by the modifying unit 140 to overcome the discrepancy.

[0117]Thus, the status of the electricity accumulating unit 200 can be
detected using Vp that causes neither an increase of SOC nor a decrease
of SOC after the end of charge and discharge.

[0118]According to this embodiment, as described above, since the
polarization voltage Vp is modified using the gradient k, the SOC
estimation can be performed with high accuracy.

[0119]The configuration and operation of a power supply according to a
third embodiment of the present invention will be described below with
reference to FIGS. 1, 8 and 9.

[0120]FIG. 8 is a block diagram showing the configuration of a processing
unit in a status detecting unit used in the power supply according to the
third embodiment of the present invention. FIG. 9 is a graph for
explaining temperature-dependent changes of internal DC resistance of an
electricity accumulating unit used in the power supply according to the
third embodiment of the present invention.

[0121]The overall configuration of the power supply according to this
embodiment is the same as that shown in FIG. 1. In this embodiment, the
processing unit in the status detecting unit is constituted as shown in
FIG. 8 described below.

[0122]A state-of-charge SOCv detecting unit 110 corresponds to the
processing unit 110 in FIG. 1 and estimates SOC based on the graph of
FIG. 4 by using the OCV obtained from the formula (2).

[0123]A state-of-charge SOCi detecting unit 112 obtains, from a current
sensor, a current I charged to or discharged from the electricity
accumulating unit 200 and calculates SOC based on the following formula
(11):

SOCi=SOC+100×∫I/Qmax (11)

[0124]An IR error detecting unit 114 calculates RI by multiplying the
current value I by the internal DC resistance R, thus obtaining an
influence of error generated. A weight deciding unit 116 decides a weight
(1/(1+RI) for SOCv and SOCi based on the error influence RI obtained by
the IR error detecting unit 114.

[0125]In general, each of detected results of voltage, current and
temperature measured using sensors includes a substantially constant
random error. Also, a current sensor generally has poorer accuracy than a
voltage sensor. Therefore, the larger the current flowing through the
electricity accumulating unit 200, the larger is an error contained in
the current value I measured by the current sensor.

[0126]When obtaining the internal DC resistance R from the characteristic
information, if the internal DC resistance R is derived corresponding to
the temperature T, the internal DC resistance R contains an error because
the temperature T obtained from a temperature sensor contains an error.

[0127]Further, when the electricity accumulating unit 200 has a modular
structure in combination of plural units, the internal DC resistance R
also contains an error due to variations in performance of individual
electricity accumulating units 200.

[0128]As shown in FIG. 9, the electricity accumulating unit 200 generally
has such a tendency that the internal DC resistance R is relatively high
at a lower value of SOC, and the value of the internal DC resistance R is
increased as the temperature of the electricity accumulating unit 200
lowers. Also, the value of the internal DC resistance R is increased with
deterioration of the electricity accumulating unit 200. The larger value
of the internal DC resistance R increases an error contained therein.

[0129]The IR error detecting unit 114 calculates the above-mentioned error
influence RI by using the current value I and the temperature T measured
by the sensors, or the former and the internal DC resistance R
corresponding to SOC. Based on the calculated RI, the weight deciding
unit 116 decides a weight (W=(1/(1+RI))) for SOCi and SOCv. For example,
the weight of SOCv is set to be smaller at a lower value of SOC, a lower
temperature, a larger extent of deterioration, or a larger current.

[0130]Assuming the weight of SOCv to be W, estimation of SOC in
combination of SOCv and SOCi is executed based on the following formula
(12):

SOCw=W×SOCv+(1-W)×SOCi (12)

[0131]To calculate SOCw based on the formula (12), a processing unit 110A
includes a subtracter DF1 for obtaining (1-W), a multiplier MP2 for
obtaining (W×SOCv), a multiplier MP1 for obtaining
((1-W)×SOCi), and an adder AD1 for adding outputs of the
multipliers MP1 and MP2.

[0132]As described above, by obtaining SOCv while modifying the
characteristic information and combining the obtained SOCv with SOCi
based on the weight W depending on RI, the status detection can be
performed with high accuracy.

[0133]The configuration of a power supply according to a fourth embodiment
of the present invention will be described below with reference to FIGS.
10-12.

[0134]FIG. 10 is a block diagram showing the configuration of a power
supply according to a fourth embodiment of the present invention. The
same reference numerals as those in FIG. 1 denote the same components.
FIGS. 11A, 11B and 11C are graphs for explaining changes of SOC when an
electricity accumulating unit in the power supply according to the fourth
embodiment of the present invention is deteriorated. FIG. 12 is a
flowchart showing processing procedures executed by a deterioration
determining unit used in the power supply according to the fourth
embodiment of the present invention.

[0135]In this embodiment, as shown in FIG. 10, a status detecting unit
100B includes a deterioration determining unit 150 in addition to the
configuration shown in FIG. 1. The deterioration determining unit 150
periodically monitors the memory unit 130 and determines deterioration of
the electricity accumulating unit 200.

[0136]When the electricity accumulating unit 200 is deteriorated, the
internal DC resistance R of the electricity accumulating unit 200 is
generally increased. In the electricity accumulating unit 200 having the
increased internal DC resistance R, an IR drop caused upon application of
the current I becomes larger than that in the initial state of the
electricity accumulating unit 200.

[0137]When SOC of the deteriorated electricity accumulating unit 200 is
estimated using the characteristic information obtained from the
electricity accumulating unit 200 in the initial state, a discrepancy
away from the theoretical value appears in the estimated result.

[0138]As shown in FIG. 11, the SOC exhibits an excessive change as the
deterioration of the electricity accumulating unit 200 progresses. More
specifically, at the stage where the electricity accumulating unit 200 is
not deteriorated, when charge is started at a time t1 as shown in FIG.
11A, the change of SOC is within a threshold Th as shown in FIG. 11B.
With the deterioration of the electricity accumulating unit 200, however,
the SOC exhibits an excessive change due to an increase of the internal
DC resistance R, as shown in FIG. 11C, to such an extent that the SOC
estimated at the start of charge exceeds the threshold Th.

[0139]The discrepancy detecting unit 120 detects such an excessive change
of SOC as being a discrepancy away from the theoretical value. If the
discrepancy is detected, the modifying unit 140 modifies the
characteristic information. In this case, the modifying unit 140 makes a
modification to increase the internal DC resistance R and stores the
increased internal DC resistance as new characteristic information in the
memory unit 130.

[0140]When the electricity accumulating unit 200 is deteriorated, the
status detecting unit 100B executes the above-described operation. When
the electricity accumulating unit 200 is further deteriorated, the
excessive change of SOC is detected again and the internal DC resistance
R is modified. In that way, the status detecting unit 100B repeats those
procedures as the deterioration of the electricity accumulating unit 200
progresses.

[0141]The operation of the deterioration determining unit 150 will be
described below with reference to FIG. 12. The deterioration determining
unit 150 monitors the characteristic information to be modified.

[0143]Then, in step S210, the deterioration determining unit 150 checks
whether any of values of the internal DC resistance R, which have been
computed depending on the SOC of the electricity accumulating unit 200,
temperature, etc., exceeds the predetermined threshold. If any value of
the internal DC resistance R exceeds the predetermined threshold, the
deterioration determining unit 150 determines that the electricity
accumulating unit 200 comes to the end of life.

[0144]The deterioration determining unit 150 can be constituted as a
microprocessor or a computer. The deterioration determining unit 150 may
monitor the characteristic information by directly accessing the memory
unit 130 as shown in FIG. 10, or may monitor the characteristic
information read out of the memory unit 130 by the processing unit 110.
Further, by providing a display unit associated with the deterioration
determining unit 150, the progress of deterioration and the result of
determining the end of life can be displayed on a display monitor or the
like.

[0145]While the deterioration determining unit 150 is shown in FIG. 10 as
being installed within the status detecting unit 100B, it may be
constituted in the form of a program module or a subroutine. In that
case, the deterioration determining unit 150 is stored as software in the
memory unit 130 and executed by the processing unit 110. When the stored
software of the deterioration determining unit 150 is executed by the
processing unit 110, the deterioration determining unit 150 monitors the
characteristic information through the above-described processing by
directly monitoring the memory unit 130 or reading the characteristic
information stored in the memory unit 130. The result of determining the
end of life of the electricity accumulating unit 200 by the deterioration
determining unit 150 is transmitted to the output unit 400 along with the
result of the status detection of the electricity accumulating unit 200.
Then, the progress of deterioration and the result of determining the end
of life can be displayed (not shown) on another microprocessor or
computer connected to the output unit 400.

[0146]The threshold used by the deterioration determining unit 150 for
determining the end of life may be set to any desired value, e.g., a
value twice or triple the internal DC resistance of the electricity
accumulating unit 200. As an alternative, the threshold may be decided
depending on the request from a system in which the electricity
accumulating unit 200 is used as a power supply.

[0147]According to this embodiment, since the characteristic information
is modified in match with the deterioration of the electricity
accumulating unit 200, the life of the electricity accumulating unit 200
can be quantitatively determined by monitoring the characteristic
information modified.

[0148]The configuration of an initial characteristic extracting device for
use with a power supply according to a fifth embodiment of the present
invention will be described below with reference to FIGS. 13-15.

[0149]FIG. 13 is a block diagram showing the configuration of the initial
characteristic extracting device for use with the power supply according
to the fifth embodiment of the present invention. The same reference
numerals as those in FIG. 1 denote the same components.

[0150]The initial characteristic extracting device of this embodiment
includes, as shown in FIG. 13, a charging/-discharging unit 500 in
addition to the power supply shown in FIG. 1.

[0151]In the power supply shown in FIG. 1, it is assumed that the
characteristic information, such as the internal DC resistance R and the
polarization voltage Vp of the electricity accumulating unit 200, is
stored in the memory unit 130 of the status detecting unit 100 in
advance. The initial characteristic extracting device of this embodiment
automatically determines the characteristic information, such as the
internal DC resistance R and the polarization voltage Vp, for each
electricity accumulating unit. The determined characteristic information
is stored in another memory unit.

[0152]When the extraction of the initial characteristic is completed, the
electricity accumulating unit 200 is assembled into the power supply to
operate as the electricity accumulating unit 200 shown in FIG. 1, and the
characteristic information stored in the other memory unit is also stored
in the memory unit 130 shown in FIG. 1 so that the power supply can be
easily initialized.

[0153]In this embodiment shown in FIG. 13, initial values of the
characteristic information first stored in the memory unit 130 can be
given by any optional values, e.g., the characteristic information of
another electricity accumulating unit 200, random numbers generated as
temporary characteristic information, or all 0.

[0154]The charging/discharging unit 500 changes the state of charge (SOC)
of the electricity accumulating unit 200 by charging and discharging the
electricity accumulating unit 200 in accordance with a predetermined
pulse pattern.

[0155]In step S300 of FIG. 14, the charging/discharging unit 500 first
charges the electricity accumulating unit 200 into an almost fully
charged state.

[0156]Then, in step S310, the charging/discharging unit 500 discharges and
charges the electricity accumulating unit 200 in accordance with the
predetermined pulse pattern. More specifically, as shown in FIG. 15, the
charging/discharging unit 500 discharges the electricity accumulating
unit 200 by applying a discharge pulse P11, and subsequently charges the
electricity accumulating unit 200 by applying a charge pulse P12.

[0157]While the charging/discharging unit 500 discharges and charges the
electricity accumulating unit 200, the measuring unit 300 obtains
measured values of the electricity accumulating unit 200 during the
discharge and the charge, and the processing unit 110 executes the status
detection of the electricity accumulating unit 200 based on the measured
values and the optionally given characteristic information. Each time the
discrepancy detecting unit 120 detects a discrepancy away from the
theoretical value, the modifying unit 140 modifies the optionally given
characteristic information in a repeated manner so that the
characteristic information is finally converged within a certain range.

[0158]After the lapse of a certain time or after confirmation of the
convergence of the characteristic information, the charging/discharging
unit 500 discharges the electricity accumulating unit 200 in step S320 by
applying a capacity adjustment pulse P13 shown in FIG. 15, thereby
lowering the SOC of the electricity accumulating unit 200.

[0159]Then, in step S330, it is determined whether the SOC is higher than
a predetermined lower limit value, e.g., 0%. If the SOC is higher than
the predetermined lower limit value, the processing of steps S310 and
S320 is repeated to modify the characteristic information by applying
pulses P21 and P22 shown in FIG. 15.

[0160]Then, if the SOC after the capacity adjustment has become lower than
the predetermined lower limit value (e.g., 0%), the processing is brought
to an end.

[0161]Instead of the above-described procedures, the process of changing
the SOC by the charging/discharging unit 500 may be performed by a method
of first setting the SOC of the electricity accumulating unit 200 to 0%,
and subsequently repeating charge and discharge for modification and
charge for capacity adjustment such that the electricity accumulating
unit 200 gradually comes into a fully charged state.

[0162]Further, by causing the charging/discharging unit 500 to charge and
discharge the electricity accumulating unit 200 while the temperature
state of the electricity accumulating unit 200 is changed, it is also
possible to modify the characteristic information depending on the
temperature state of the electricity accumulating unit 200. In such a
case, a thermostatic chamber (not shown), for example, is employed to
keep the electricity accumulating unit 200 at a specified temperature.
The set temperature of the thermostatic chamber is changed each time the
process of discharging and charging the electricity accumulating unit 200
by the charging/discharging unit 500, described above with reference to
FIG. 14, is completed. The set temperature of the thermostatic chamber
may be changed by a manner of gradually raising the temperature from a
low to high level or gradually lowering the temperature from a high to a
low level whenever the discharging and charging process shown in FIG. 14
is completed.

[0163]According to this embodiment, as described above, the characteristic
information can be automatically modified depending on various states,
and the initial characteristic of the electricity accumulating unit 200
can be extracted.

[0164]The configuration of a second initial characteristic extracting
device for use with a power supply according to a sixth embodiment of the
present invention will be described below with reference to FIGS. 16 and
17.

[0165]FIG. 16 is a block diagram showing the configuration of the second
initial characteristic extracting device for use with the power supply
according to the sixth embodiment of the present invention. The same
reference numerals as those in FIG. 1 denote the same components. FIGS.
17A and 17B are charts for explaining an initial characteristic
extracting method in the power supply according to the sixth embodiment
of the present invention.

[0166]This embodiment includes a charging/discharging unit 510 instead of
the charging/discharging unit 500 shown in FIG. 13. Characteristics of
the charging/discharging unit 510 will be described with reference to
FIG. 17.

[0167]This embodiment further includes a characteristic extracting unit
600. The characteristic extracting unit 600 contains the characteristic
information regarding the relationship between the electromotive force
(OCV) and the state of charge (SOC), and extracts a characteristic of the
electricity accumulating unit 200 by using measured values obtained from
the measuring unit 300.

[0168]The charging/discharging unit 510 outputs a current signal having a
pulse pattern, shown in FIG. 17A, to charge the electricity accumulating
unit 200. A voltage measured at this time is changed as shown in FIG.
17B.

[0169]The characteristic extracting unit 600 takes in the measured values
for a predetermined time while a current I shown in FIG. 17A is applied.
The characteristic extracting unit 600 first obtains, from among the
taken-in measured values, a voltage Va immediately before the application
of the current I. Because the voltage Va represents an electromotive
force (OCV1) of the electricity accumulating unit 200, the SOC of the
electricity accumulating unit 200 before the application of the current I
is determined from the relationship between OCV and SOC, which has been
obtained in advance. The voltage Va is taken as a voltage value at the
timing before an abrupt increase of the current value, while monitoring
the current value among the measured values. Also, the characteristic
extracting unit 600 obtains temperature information among the measured
values in succession. Thus, the characteristic extracting unit 600
enables the status of the electricity accumulating unit 200, such as the
SOC and the temperature, to be automatically detected before the
application of the current I.

[0170]A description is now made of the operation of the characteristic
extracting unit 600 when the electricity accumulating unit 200 is charged
with the current I. In general, at the moment when the electricity
accumulating unit 200 is charged with the current I, the voltage of the
electricity accumulating unit 200 is increased by IR. Upon the end of the
charge, a voltage drop IR occurs and thereafter a drop of the
polarization voltage Vp occurs. In other words, by using voltages Vb, Vc
and Vd shown in FIG. 17B, the internal DC resistance R and the
polarization voltage Vp can be calculated respectively from the following
formulae (13) and (14):

R=(Vb-Vc)/1 (13)

Vp=Vc-Vd (14)

[0171]Here, because the voltage Vb represents a voltage just before the
end of the charge with the current I, it can be readily detected by
monitoring the current I. The voltage Vc represents a voltage after the
occurrence of the voltage drop IR. The voltage Vc may be decided in an
automatic way as a voltage value after a certain time from the end of the
charge with the current I. An alternative manner is as follows.
Generally, when a voltage change after the end of charge of the
electricity accumulating unit 200 exceeds a predetermined threshold, the
voltage change represents the voltage drop IR, and when that voltage
change does not exceed the predetermined threshold, it represents the
polarization voltage drop. Therefore, when the voltage change not
exceeding the predetermined threshold is detected as a result of
monitoring the voltage value after charging the electricity accumulating
unit 200 with the current I, the voltage at that time can be detected as
Vc. Also, because the voltage Vd represents a voltage at a time where the
voltage change has disappeared after the end of the charge with the
current I, it can be readily detected by monitoring an amount of the
voltage change. Additionally, the voltage Vd represents an electromotive
force (OCV2) of the electricity accumulating unit 200 after the end of
the charge with the current I.

[0172]From the characteristic information between the electromotive force
(OCV) and the state of charge (SOC), the SOC of the electricity
accumulating unit 200 after being charged for a predetermined time with
the current I can also be readily computed. Further, by using a time from
the detection of Vc to the detection of Vd, a delay time (time constant)
τ of the polarization voltage drop can be readily computed.

[0173]Moreover, by using an amount of charge J I after the charge for the
predetermined time with the current I, SOC1 obtained from OCV1 before the
charge, and SOC2 obtained from OCV2 after the charge, a fully charged
capacity Qmax of the electricity accumulating unit 200 can be readily
computed from the following formula (15):

Qmax=100×∫I/(SOC2-SOC1) (15)

[0174]The internal DC resistance R, the polarization voltage Vp, the time
constant τ, and the fully charged capacity Qmax may be determined for
one value of the current I, or may be obtained by a manner of determining
plural values of each parameter while variously changing the current I
and calculating an average of those plural values.

[0175]Thus, the characteristic extracting unit 600 can automatically
compute not only the present temperature and SOC of the electricity
accumulating unit 200, but also the characteristic information, such as
the internal DC resistance R, the polarization voltage Vp, the time
constant τ, and the fully charged capacity Qmax, corresponding to
those present conditions. The computed data of the characteristic
information are stored as initial values in the memory unit 130.

[0176]Further, by employing the pulse pattern described above with
reference to FIGS. 14 and 15, the characteristic information
corresponding to various states of charge can be computed. By adjusting
the temperature of the electricity accumulating unit 200 using a
thermostatic chamber, the characteristic information corresponding to
various temperatures and various states of charge of the electricity
accumulating unit 200 can also be computed in an automatic manner.

[0177]In addition, by applying the above-described manner of computing the
characteristic information to the case of discharging the electricity
accumulating unit 200 with the current I, the characteristic information
corresponding to the temperature and the state of charge of the
electricity accumulating unit 200 during discharge can also be computed
in an automatic manner.

[0178]The characteristic information computed by the characteristic
extracting unit 600 is stored in the memory unit 130. On that occasion,
the characteristic extracting unit 600 may directly transmit the
characteristic information to the memory unit 130 for storage therein, as
shown in FIG. 16. Alternatively, the characteristic information may be
transmitted to the processing unit 110 such that the processing unit 110
stores the characteristic information in the memory unit 130.

[0179]The characteristic extracting unit 600 can be constituted as a
microprocessor or a computer executing the above-described processing.

[0180]After completing the extraction of the characteristic information as
described above, the characteristic extracting unit 600 transmits the
received measured values, as they are, to the processing unit 110 or the
discrepancy detecting unit 120.

[0181]As an alternative, the characteristic extracting unit 600 may be
constituted in the form of a program module or a subroutine executing the
above-described process. In that case, the characteristic extracting unit
600 is stored in the memory unit 130 as software executing the
above-described process, and those procedures are executed by the
processing unit 110. When the above-described process of the
characteristic extracting unit 600 is completed, the processing unit 110
executes the status detection of the electricity accumulating unit 200 by
using the characteristic information that has been prepared by the
characteristic extracting unit 600.

[0182]After the processing unit 110 executes the status detection of the
electricity accumulating unit 200 by using the characteristic information
prepared by the characteristic extracting unit 600, the discrepancy
detecting unit 120 monitors whether there is a discrepancy away from the
theoretical value. Further, the modifying unit 140 modifies the
characteristic information by the predetermined modification amount as
described above.

[0183]Thus, the provision of the characteristic extracting unit 600
enables the initial characteristic information to be automatically
determined, the discrepancy detecting unit 120 performs monitoring based
on the determined characteristic information, and the modifying unit 140
modifies the characteristic information. Therefore, the initial
characteristic can be extracted with high accuracy.

[0184]The configuration of a third initial characteristic extracting
device for use with a power supply according to a seventh embodiment of
the present invention will be described below with reference to FIGS. 18
and 19.

[0185]FIG. 18 is a block diagram showing the configuration of the third
initial characteristic extracting device for use with the power supply
according to the seventh embodiment of the present invention. The same
reference numerals as those in FIG. 1 denote the same components. FIG. 19
is a chart for explaining an initial characteristic extracting method in
the power supply according to the seventh embodiment of the present
invention.

[0186]This embodiment includes two or more electricity accumulating units
200A and 200B and a charge/discharge control unit 700 for controlling
charge and discharge of two or more electricity accumulating units 200A
and 200B.

[0187]As shown in FIG. 19, the charge/discharge control unit 700 controls
charge and discharge of currents between the electricity accumulating
units 200A and 200B. More specifically, the charge/discharge control unit
700 discharges the electricity accumulating unit 200A and charges the
electricity accumulating unit 200B with the discharge current from the
former unit 200A. Also, the charge/discharge control unit 700 discharges
the electricity accumulating unit 200B and charges the electricity
accumulating unit 200A with the discharge current from the former unit
200B. When the electricity accumulating units 200A and 200B of the same
type are charged, the voltage in the discharge side may be boosted using
a DC/DC converter, etc. Also, when the voltage in the charge side is
lower than that of the electricity accumulating unit in the discharge
side, the voltage in the discharge side may be lowered. By repeating the
above-mentioned process, charge and discharge can be performed between
the two electricity accumulating units 200A and 200B in the same manner
as that using a pulse pattern.

[0188]In operation, charge and discharge are performed between the
electricity accumulating units 200A and 200B, and the measuring unit 300
obtains measured values during the charge and the discharge. The
processing unit 110 executes the status detection of each electricity
accumulating unit 200 based on the measured values and the optionally
given characteristic information. The discrepancy detecting unit 120
monitors whether there is a discrepancy away from the theoretical value,
and the modifying unit 140 modifies the optionally given characteristic
information. After repeating that process, the finally converged
characteristic information is employed as an initial characteristic of
the corresponding electricity accumulating unit 200.

[0189]The electricity accumulating units 200A and 200B may be of the same
type or a combination of different types, such as a lithium ion battery
and a lead-acid battery, a lithium ion battery and a nickel-hydrogen
battery, or a nickel-hydrogen battery and a lead-acid battery. Further,
the two or more electricity accumulating units 200A and 200B may be each
of a modular structure including a plurality of electricity accumulating
units 200 combined with each other.

[0190]While the measuring unit 300 for obtaining the measured values of
the electricity accumulating units 200A and 200B is shown only one in
FIG. 18, it is actually provided for each of the electricity accumulating
units 200A and 200B to obtain the measured values of the corresponding
electricity accumulating unit. In other words, when there are two
electricity accumulating units 200, two measuring units 300 are provided
to obtain respective measured values of the two electricity accumulating
units 200 and transmit the measured values to the processing unit 110 or
the discrepancy detecting unit 120.

[0191]The characteristic information stored in the memory unit 130 may be
one kind of data set when the electricity accumulating units 200A and
200B of the same type are provided, or may be different specific kinds of
data sets even when the electricity accumulating units 200A and 200B of
the same type are provided. Also, the processing procedures stored in the
memory unit 130 to execute the status detection are prepared as one kind
of procedures when the electricity accumulating units 200A and 200B are
the same type. When the electricity accumulating units 200A and 200B are
different types, the status detection can also be performed using one
kind of processing procedures common to both the units, or may be
performed using different kinds of processing procedures dedicated for
the respective kinds of the electricity accumulating units 200A and 200B.

[0192]The processing unit 110 receives the measured values for each of the
electricity accumulating units 200A and 200B, and executes the status
detection for each of the electricity accumulating units 200A and 200B by
using the characteristic information of the corresponding electricity
accumulating unit, which is stored in the memory unit 130. The processing
unit 110 may be provided one common to the plurality of electricity
accumulating units 200A and 200B, or one dedicated for each of the
electricity accumulating units 200A and 200B.

[0193]Similarly to the processing unit 110, the discrepancy detecting unit
120 and the modifying unit 140 may be each provided one common to the
plurality of electricity accumulating units 200A and 200B, or one
dedicated for each of the electricity accumulating units 200A and 200B.

[0194]With the above-described configuration, the status detection of the
two or more electricity accumulating units 200A and 200B is performed,
and when the discrepancy detecting unit 120 detects a discrepancy away
from the theoretical value, the modifying unit 140 modifies the
characteristic information.

[0195]In this way, the initial characteristic of the characteristic
information can be obtained by performing charge and discharge between
two or more electricity accumulating units.

[0196]The configuration of a fourth initial characteristic extracting
device for use with a power supply according to an eighth embodiment of
the present invention will be described below with reference to FIG. 20.

[0197]FIG. 20 is a block diagram showing the configuration of the fourth
initial characteristic extracting device for use with the power supply
according to the eighth embodiment of the present invention. The same
reference numerals as those in FIG. 1 denote the same components.

[0198]In this embodiment, the characteristic extracting unit 600 described
above with reference to FIG. 16 is additionally associated with the
initial characteristic extracting device shown in FIG. 18. More
specifically, two or more electricity accumulating units 200A and 200B
are provided, and the charge/discharge control unit 700 performs charge
and discharge between the electricity accumulating units 200A and 200B.
The measuring unit 300 obtains measured values during the charge and the
discharge, and the characteristic extracting unit 600 extracts
characteristic information based on an analysis using the measured
values. The processing unit 110 executes the status detection for each of
the electricity accumulating units 200A and 200B based on the extracted
characteristic information and the measured values. The discrepancy
detecting unit 120 monitors whether there is a discrepancy away from the
theoretical value, and the modifying unit 140 modifies the characteristic
information.

[0199]In this way, the initial characteristic of the characteristic
information can be obtained by performing charge and discharge between
two or more electricity accumulating units.

[0200]According to the present invention, as described above, the state of
charge of the electricity accumulating unit can be estimated with high
accuracy. Also, the life of the electricity accumulating unit can be
quantitatively determined. Further, the initial characteristic of the
electricity accumulating unit can be extracted. These advantageous
features are applicable to a wide range of fields including mobile
equipment, UPS (Uninterruptible Power Supply), and vehicles such as HEV
(Hybrid Electric Vehicle) and EV.